The invention relates to a novel, multi-functional fuel additive and fuel composition containing said additive.
Fuels are susceptible to chemical reaction on aging. One effect of oxidation is to produce soluble and insoluble materials of higher molecular weight and boiling point than the original fuel. The deterioration due to oxidation and the like of distillate fuels, particularly in diesel fuel, manifests itself, for example, through the appearance of color and gums. The tacky oxidized fuel deposits adhere readily to injector parts and can cause injector sticking, nozzle-hole plugging and leakage past critical surfaces.
Also, diesel engines are equipped with fuel filters to remove particulate matter from the fuel. Any gums which are present in the fuel tend to coat onto the filter, requiring frequent changes of the filter in order to permit adequate fuel flow as well as effective filtering action.
While many materials might effectively act as commercially successful dispersants for the gum, the field is severely limited to relatively few materials. Also, since the dispersant is an additive to the fuel, it must not significantly increase the deposits created in the combustion chamber, which interfere with the proper functioning of the piston. In order to have an acceptable fuel dispersant, it is not only necessary that the dispersant maintain the gums dispersed in the fuel mixture, but the dispersant itself, when introduced into the combustion chamber, should not form deposits which significantly interfere with the operation of the piston.
Polyalkylene amines, particularly polybutene amines, are well known as providing excellent detergency in spark ignition engines. See, for example, U.S. Pat. No. 3,438,757 or 3,898,065, which disclose various amines as having excellent detergency and dispersancy properties in fuels.
The Mannich condensation reaction is well known in the art and involves the reaction of an alkylphenol, an aldehyde and an amine. Mannich bases and the metal phenates derived therefrom have been used in lubricants and fuels as anti-oxidants and dispersants. See, for example, U.S. Pat. Nos. 2,353,491, 2,363,134, 3,454,497 and 4,025,451.